Tibia and Fibula
The tibia that and it connects the knee with the ankle bones. It is located medially to the fibula. It consists of a two epiphyses and a shaft. Osteology The upper epiphysis: expanded into the articular medial and lateral condyle, termed tibial plateau. The surfaces are flattened and gently concave for articulation with the menisci and condyle of the femur. The medial condyle is larger and oval while lateral condyle is more circular and smaller. * The back of the medial condyle is grooved for semimembranosus attachment * The lateral condyle carries facet for head of fibula and the groove for popliteus tendon. Anteriorly it carries the Gerdy's tubercle for insertion of the iliotibial tract. From the tubercle, a ridge sloped down into the tibial tuberosity for insertion of the patellar ligament. The condyles are separated by the non-articular intercondylar eminence, a rough bony elevation. It contains medial and lateral intercondylar tubercles. The anterolateral region of the anterior intercondylar area are perforated by numerous small openings for nutrient arteries. Six facets are present for the attachment of the cruciate ligaments and menisci: * anterior horn of the lateral meniscus: anterior to the medial intercondylar tubercle * posterior horn of the lateral meniscus: posterior to the lateral intercondylar tubercle * anterior horn of the medial meniscus: at the anterior margin of the intercondylar area * posterior horn of the medial meniscus: anterior to the attachment of the posterior cruciate ligament * anterior cruciate ligament: medial to the anterior horn of the lateral meniscus attachment * posterior cruciate ligament: posterior margin of the intercondylar area The shaft: triangular in section with anterior, medial and lateral (interosseous) border and three surfaces; the medial, lateral and posterior. * Medial surface: subcutaneous. and receive tendons of sartorius, gracilis and semitendinosus at the pes anserinus. It continues into the medial malleolus. * Lateral surface: origin of the anterior compartment muscle of the leg * Posterior surface: origin of the deep posterior muscle of the leg. The soleal line runs down obliquely to one third of the way down. * Medial border: saphenous nerve and vein run along it * Lateral border: ridge for attachment of interosseous membrane * Anterior border: sharp ridge running from tibial tuberosity to the medial malleolus. The lower epiphysis: extended as a prominent medial malleolus distally. It is rectangular in section. * Medial surface: subcutanoues, great saph vein and nerve crosses it. * Anterior surface - bare bone crossed by tendons of tibilas anterior, EHL and anterior tibial neurovasular bundle. * Lateral surface - interosseous ligament * Posterior surface - groove behind medial malleolus for tendon of tibalis posterior. Joints The tibia is a part of four joints; the knee, ankle, superior and inferior tibiofibular joint. * Knee: the tibia forms one of the two articulations with the femur, often referred to as the tibiofemoral components of the knee joint. This is the weightbearing part of the knee joint. * The proximal tibiofibular joint: a small plane joint. The joint is formed between the undersurface of the lateral tibial condyle and the head of fibula. The joint capsule is reinforced by anterior and posterior ligament of the head of the fibula. * The distal tibiofibular joint (tibiofibular syndesmosis) is formed by the rough, convex surface of the medial side of the distal end of the fibula, and a rough concave surface on the lateral side of the tibia. * Ankle joint: talocrural joint, is a synovial hinge joint that connects the distal ends of the tibia and fibula in the lower limb with the proximal end of the talus. Blood supply Anterior tibial artery * nutrient artery * periosteal vessels Ossification: three centers * Shaft 7 weeks in utero, and gradually extends toward the extremities. * Upper epiphysis appears at birth and close at 20 years. * Lower epiphysis appears 4 months to 1 year and fuses with shaft at 18 years * Tibial tuberosity at 10-12 years. Two additional centers occasionally exist, one for the tongue-shaped process of the upper epiphysis, which forms the tuberosity, and one for the medial malleolus. Variation * Additional articular facets on anterior surface of tibia * Bony canal for anterio tibial artery * Absence of tibia or fibula * Primary variant are the form, length and size of the shaft, i.e. lateral malleolus not grooved by convex. ** In the male, its direction is vertical, and parallel with the bone of the opposite side. In the female, it has a slightly oblique direction downward and laterally, to compensate for the greater obliqueness of the femur.